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Model 5528A
Distance Measurements
6·28
b.
Multiply the number you ju st ent
ered
(1.5
x
10
-6)
by
th
e
length of travel (508 mm
,
or
20
inches)
ar,d
er,ter
th
e
product in column
" B"
(0,00080
nun
,
or 0.00031
irK
h
).
5.
Identify
th
e
accuracy
of yo
ur material temperature
compensa tio n.
a.
Ident
ify t he
type of
materia
l
you
are measuring.
b.
Dete
rmine
this
mat erial
's coe
fficient
of
thermal
eKpansion.
Some
typica
l
val ues are
pre·
sented
below.
For
our example, we'll
use "steel".
steel
'"
11.7 ppm per
degree Celsi us
aluminum
"
23.6
ppm per
desree Celsi us
co
pper
=
16.5
ppm per degree
Celsi us
c.
Identify the accura
cy
of your
temperature
sensor.
The
10757
Material
Sensor
hasa
sped·
lied
accuracy
of
±O.10oC,
as
shown
on The
"
Error Budget Worksheet"
,
(These
values are
also given
in the la
se
r
Measurement System's Service
Manual
).
Mul tiply
this
accuracy
by
the expansion
cotd
ficient and enter the produCi
in
column
"
A"
11
.2
ppm).
NOTE
To attain th
e
specified
aCClrracy
of
±0.10oC,
the
output
chara cteristi
cs
of the
10757
Material
Sensor
mu st be mat ched to particular 550UA
Measurem ent Di spla
y.
Plea se refcr to the
calibration
matching
prace·
dure in Section
4·
45 in
the
laser Measurement
System's
Service
Manual.
d.
Multiply
th
e
accuracy
value you
Just
calculated
(1.2
ppm
)
b
y
the
length
of
travel (508 mm
,
or
20 in
ches)
and
enter
in
column
" B"
(0.00061
mm
,
or 0.000024
in ch
).
6.
Since you should
alwa
ys be
starting
your
mea
su rements
when the
Optics
are close
together,
assume
tha
t
the
error
due to deadpath
will always
be neg ligible.
7.
Multipl
y
0.1 ppm
~
the
accuracy
lim ita tion
of
the
laser Measurement
System
itself)
by
the
length
of
tra vel
~
S08
mm, or 20
in
ches)
and enter
the product
in
co
lumn
" 8"
~
O
,OOOO5
mm,or
0.000002
in ch
).
8.
Identify
the magnitude
of
the cosin
e
error
in
your
setup
-
a.
Identif
y
how
much
molion
there is
between
the
two return
dots
if
the
Optics arc moved
over
the
entire
measuremen
t
axis.
(The
laser
Head's exit
port
should ha
ve
the small
opening
for
this,
and the
return port should ha
ve
the target in
place.)
The
smallest
move
ment
you
are IIk e(y to detect
will
be
about
0.25
mm (0.010 inch
).
This
value
will be
"S"
in
the
formula
below.
For
o
ur
example,
we'
ll
let
"5"
=
"
0.25
nun
"
(0.010
inch
).
b
.
Enler the
length
of
Optic
tra
ve
l
as
"D" in the
formula
below.
c.
The
cos
ine
error in
yo
ur setup
is
-
E
-
~
in
parts-pcr·
million,
or
E
X
D, in absolute
terms
60
,
w here
-
"S"
is
the
movement between
return dot
s,
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